PR c++/84801 - ICE with unexpanded pack in lambda.

	We avoid complaining about unexpanded packs when inside a lambda,
	since the lambda as a whole could be part of a pack expansion.
	But that can only be true if the lambda is in a template context.

   	* pt.c (check_for_bare_parameter_packs): Don't return early for a
	lambda in non-template context.

From-SVN: r258548

gcc/cp/ChangeLog

 2018-03-14  Jason Merrill  <jason@redhat.com>
 
+	PR c++/84801 - ICE with unexpanded pack in lambda.
+	* pt.c (check_for_bare_parameter_packs): Don't return early for a
+	lambda in non-template context.
+
 	PR c++/81236 - auto variable and auto function
 	* pt.c (tsubst_baselink): Update the type of the BASELINK after
 	mark_used.

gcc/cp/pt.c

@@ -4043,7 +4043,8 @@ check_for_bare_parameter_packs (tree t)
     return false;
 
   /* A lambda might use a parameter pack from the containing context.  */
-  if (current_class_type && LAMBDA_TYPE_P (current_class_type))
+  if (current_class_type && LAMBDA_TYPE_P (current_class_type)
+      && CLASSTYPE_TEMPLATE_INFO (current_class_type))
     return false;
 
   if (TREE_CODE (t) == TYPE_DECL)

gcc/testsuite/g++.dg/cpp1y/lambda-generic-variadic15.C

+// PR c++/84801
+// { dg-do compile { target c++14 } }
+
+int v;
+int main() { [](auto... c) { v = c; }(1); } // { dg-error "not expanded" }